running rich- still -

[Ben Swann]

Well it sounds like you are on finding the problem - just need to follow through.

Regarding the temp sender - 3500 is not necessarily that far out - just telling the ECU
the engine is cold, but how cold was it?  That plus you may have added resistance
somewhere in the wiring and the sensor is OK, just the combination is making up the
higher resistance.  So try cleaning the contacts and check for marginal wiring.  AFAIK
the sensor is NTC, so resistance should go down as engine warms up - you need to verify
this and make sure things come into spec as car warms up.

The TPS can definitely be a problem.  As with many of the sensors, if not completely out
of range, the ECU will not necessarily throw a code and TPS has no built in checking.
Unless the wiring is bad - broken or shorted to ground, most likely ECU will not gen. a
code.  The sensors do fail, but IME, wiring is usually more of a culprit and adjustment
can be tricky with the idle switch portion. Make sure all these are working properly
with VOM and Bentley has some tests.  

Re. fuel smell.  I'd be checking for leaky/weeping fuel line or problem with carbon
canister valve.

Ben

[Date: Mon, 26 Nov 2007 09:49:18 -0700
From: "Brandon Rogers" <brogers at terrix.com>
Subject: RE: running rich- still -
To: "'200 20v List'" <200q20v at audifans.com>
Message-ID: <004e01c8304c$49ba4110$2c01a8c0 at BCROGERS>

So I replaced the thermo switch/temp sender in the back of the head - no change.
 
Anybody ever had a Throttle Pos Sensor go bad and not throw a code?
 
And I _think_ I'm only rich at idle and maybe on decel - does that shed any light on the
potential issue?  Thats why I'm thining TPS now - maybe its not telling the ECU to go
into Decel and Idle mixture.....???????
 
As a "reminder" - I have replaced within the last year or two- FPR w/ new rubber vac
line ~2 yrs ago
02 sensorThermo time/temp sender 11/07 had injectors serviced by RC Engineering 9/07 No
leaks - pressure tested 11/07 checked vac line to FPR 11/07 Cap/rotor/plugs 4 yrs/20k
miles old IAT wiring renewed 11/07
 
Should I check my fuel pressure?
 
Any input appreciated -
 
TIA-
 
Brandon
'84 urquattro 20V
 

-----Original Message-----
From: Brandon Rogers [mailto:brogers at terrix.com]
Sent: Monday, November 19, 2007 1:51 PM
To: '200 20v List'
Subject: running rich- temp sender


Guys-
so as I still try to figure why I always get a very rich exhaust smell wafting into the
cabin when I come to stop - I tested the temp sender (white two pin back of head)-
Bentley says resistance should be
1500-3000 Ohms when cold (68F).  Mine was 3500.  Anybody had a temp sender go bad - what
happened?  Anybody feel like getting crazy and checking to see what value you get on
yours? - check resistance across the 2 pics when cold.
 
any thoughts appreciated
 
Brandon]